a). Field of the Invention
The present invention relates to a manufacture method of a semiconductor device including a wiring layer forming process. More particularly, the invention relates to a manufacture method of a semiconductor device capable of forming an insulating film in short time by using a hydrogen silsesquioxane resin, which film has a good surface flatness and is excellent in resistance to chemicals.
b). Description of the Related Art
As an insulating film having a planarizing function, a spin-on-glass (SOG) film is known. The film quality of this SOG film is inferior, however, to a chemical vapor deposition (CVD) oxide film. A manufacture method of a semiconductor device such as LSIs illustrated in FIGS. 9 and 10 has been conventionally used (for example, refer to JP-A-7-283310).
At the process shown in FIG. 9, a MOS transistor generally indicated at T and having a lightly doped drain (LDD) structure is formed on the surface of a semiconductor substrate by a well-know method. In this transistor T, F indicates a gate insulating film made of silicon oxide or the like, G indicates a gate electrode layer made of polysilicon, polycide, or the like, Ps and Pd indicate side spacers made of silicon oxide or the like, S indicates a source region including an n.sup.- region under the side spacer Ps and an n.sup.+ region outside of the side spacer Ps, and D indicates a drain region including an n.sup.- region under the side spacer Pd and an n.sup.+ region outside of the side spacer Pd.
Next, an insulating film 2 of silicon oxide is formed over the surface of the substrate 1 by CVD, the insulating film 2 covering the transistor T. On this insulating film 2, an SOG film 3 containing a silanol group is coated by spin-coating or the like to have a flat surface. The SOG film 3 is subjected to low temperature annealing at 150.degree. C. for 30 minutes, at 300.degree. C. for 30 minutes and then at 400.degree. C. for 30 minutes in a nitrogen gas atmosphere. Thereafter, high temperature annealing is performed at 850.degree. C. in an oxidizing atmosphere of water vapor. This high temperature annealing in the oxidizing atmosphere is used for making the quality of the SOG film dense.
Thereafter, a contact hole 4 reaching a partial area of the drain region D is formed through the lamination of the insulating film 2 and SOG film 3 by well-known photolithography and selective etching.
At the process shown in FIG. 10, the inside of the contact hole 4 is washed with diluted hydrofluoric acid in order to remove a natural (or native) silicon oxide film formed on the silicon surface at the bottom of the contact hole 4. Wiring material is then deposited over the substrate surface and patterned to form a wiring pattern 5 which is connected in this state to the partial area of the drain region D via the contact hole 4.
If the high temperature annealing is performed not in an oxidizing atmosphere but in a non-oxidizing atmosphere such as a nitrogen atmosphere, an etching rate during the washing process with diluted hydrofluoric acid may become abnormally fast at some region of the SOG film 3 and may form a void V. If such a void V is formed, a portion of the wiring material may enter the void V so that short circuit between the wiring pattern 5 and another wiring pattern may be formed or the contact state of the wiring pattern 5 may be deteriorated.
However, with the above method, the SOG film 3 is made dense by the high temperature annealing in the oxidizing atmosphere. Therefore, it is possible to prevent the formation of such a void V communicating with the contact hole 4 during the washing process with diluted hydrofluoric acid. Preventing the formation of a void V improves the manufacture yield of a wiring pattern and the reliability of the wiring pattern.
The above conventional method is required to perform high temperature annealing for a long time in the oxidizing atmosphere, in order to prevent the formation of a void V. It has been found that such a long time high temperature annealing deteriorates the electric characteristics of the transistor T.